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Feb: 9 i

- 1 vc. WELHJELM v SAFETY I DEVICE FOR CONTROL INSTRUMENTS ATTO/f/VEY LIA/E Filed Sept. 9. 1922 Patented Feb. 12, 1224. I

CHRISTIAN WILHJELM, OF PHILADELPHIA, I ENNSYLVANIA, ASSIGNOR TO THE BROWN INSTRUMENT COMPANY, OF -TION OF PENNSYLVANIA.

PHILADELPHIA, PENNSYLVANIA, A CORPORA- SAFETY DEVICE FOR CONTROL INSTRUMENTS.

Application filed September 9, 1922. Serial No. 587,252.

To all whom it may concern:

Be it known that I, CHRISTIAN \VILHJELM,

a subject of the King of Denmark, and a resident of Philadelphia, county of Philadelphia, State of Pennsylvania, have invent ed certain new and useful Improvements in Safety Devices for Control Instruments, of which the following is a specification.

Some of the objects of the present inven tion are to provide means operating in con junctionwith a control-instrument for automatically shutting down the controlledm-y dium in case the instrument or parts thereof cease to function in the proper manner; to provide a safety device for control instruments to prevent abnormal conditions arising should the instrument fail to control the medium which is responsive tothe instrument; to provide an electrically operated means for .pse with a temperature control instrument for shutting down a heating medium controlled by said instrument, said means beingrendered inactive by said instrument under normal conditions of opera tion, and being rendered active under inoperative conditions of said instrument; to provide means for discontinuing the operation of a heating or other medium controlled by an electrical. instrument and simultaneously rendering said instrument ineffective for control purposes; to provide, in a depressor actuated control instrument, means under the control of said depressor operating mechanism for cutting off the medium controlled by the instrument in case the de-' pressor mechanism ceases to function; and

to provide other improvements as will hereinafter appear.

In the accompanying drawings, Fig. 1 represents a front elevation of a measuring instrument with parts broken away to show diagrammatically one form of the present invention in safety controlmeans for elec. trical instruments; and Fig. 2 represents diagrammatically a heat control mechanism controlled by the instrument of Fig. 1.

Referring to the drawings, one form of the presentinvention is here shown as arranged for operation in a temperature measuring instrument 10 of the type having a pointer 11 which is operated by any well known means responsive to temperatures at a furnace or zone, the' temperature of whlch is to be measured or controlled. The present instrument comprises a contact table 12 having two fixed contacts 13 and 14 and two movable contactors 15 and 16 arranged to respectively engage the said contacts according to the position ofthe pointer, 11 when engaged by a depressor bar 17 which is periodicallyjoperated by a rod 18 through the medium of a cam 19 driven by a Warren motor 20 or any other suitablemeans. The contact 13 and contactor 15 form terminals of a circuit means arranged to cause'the heating unit to supply heat, and the contact 14 and contactor 16 form terminals of a circuit means arranged to cause the heating unit to cut oil the heat supply. The

supply control circuit includes conductor 21, and terminal post L, common return post C and conductor 22, and the cut off supply control circuit includes conductor 23, termi nal post H, common return post C, con-- ductor 22 and conductor 24.

The aforesaid circuits are arrangedto operate a switch or other heat control mechanism which consists, for example, of a reciprocable rod 25, so connected as to open and close a fuel valve, or actuate an electric switch, or cause any other device to function whereby the heating of a furnace or other unit is controlled. In the present conarm 26 pivoted at 27 to a fixed part 28, and

rod and to the common core 30 of a double coil solenoid 31. The windings 32 and 33 of the solenoid 31 are reversely wound with-- respect to'each other, the winding 32 having oneend connected by a conductor34 to the post L, and the other end connected by'a conductor 35 to a common return conductor 36. The winding 33 has one end connected by a conductor 37 to the post H, and its other end connected by the conductor 36 to one side of the service line. The opposite side of the service line is connected by a condi1ctor38 to the post C. H

.In order to provide a means for automatically-causing the heating-unit to shut down in case the motor stops, or for any reason the depressor bar 17 ceases to function, a safety control mechanism .is .provided, which in the present form of'the inc invention comprises a thermostatic .swi'tch' 40 consisting of two arms 41 and 42 formed of thermostatic metal moun ed in spaced relation by blocks 43 which secure between them a third arm.'44 also of thermostatic metal. The blocks 43 are of insulating material to electrically separate the arm 44 from the arms 41 and 42, and these last arms are electrically connected by a conductor 45 which traverses a relay coil 46 on its wayto the post H. The arm 41 is provided with a contact 47 arranged in the path of a contactor 48 on the arm 44, while the'arm 42 is provided with a contact 50 arranged in the I path of a contactor 51 on the arm 44. The

three contact arms are held at one end by the blocks 43 so that the other ends of each are freeto move under variations of temperature, the arrangement being such that the contacts 47 and 50 are always spaced substantially the same distance apart, while the arm 44 is normally bent to hold its contactor 51 against the contact 50. A cir- .cuit is thus normally closed from post H, conductor 45 through arms 42 and 44 and by way of a conductor 52 to post C. This is the circuit which energizes the winding 33 and causes the control rod 25 to shut off the source of heat.

As a means for breaking the aforesaid normally closed circuit to bring the control mechanism of the rod 25 under the control of the instrument 10, the contactor arm 44 is wound witha coil 53 of resistance wire, one end of whichis connected by a conductor 54 to a post 55 for connection to one side of the service line, while the other end is connected by a conductor 56 leading through a non-inductive resistance 57 to a contact strip 58 provided with a contact 60.' This arm 58 .is suitably mounted to hold its contact 60 in juxtaposed relation to a contactor 61 fixed to a flexible contactor strip 62 which is insulated from the strip'58 and is bonded to a conductor 63 leading to a post 64 for connectionto the opposite side of the service line from the post 55. The resistance 57 and windingo'f the coil 53 are so adjusted that whencurrent is flowing in the coil circuit, for a relatively short interval, the

thermostatic arm 44 will be heated and bend to a position between the arms 41 and 42 so that the contacts 48. and 51 are both in a neutral or non contacting period of current flowing is etermined .by' the closing of the contact 60 and contactor 61 under the action of a"'finger 65 rigidly secured to the depressor rod 18 in position to pick up the contactor strip 62 at each reciprocation of the rod 18. Thus the circuit of the coil 53 as long, as the intermittent depressions of min the neutral parts of the is closed periodically and the contactor strip 62 follow each other. at. regular intervals the heating'of the coil 53 is only suficlent to maintain the arm 44 position. Hence, when 'all lnstrument are functioning. properly, the heating controlymechanism' is (position. The Y Y ger \6 ag in t arm switch 66 which is in series with the low temperature circuit including contact 13. This switch 66 has a. contactor 67 held by sprmg tension against a fixed contact 68 until the relay coil 46 is energized. The contact 68 is connected by a conductor 70 to the 'post L to complete the, controlci'rcuit.

The operation of the safety control with the instrument is as follows: With no current on the rod 25 is in the position to cut oil the supply of heat, and the control-thermostatic safety switch has its arm 44 bent.

to bring v the together.

contact 50 and con-tactor51 When the current is turned on the motor 21 operates to periodically reciprocate the rod 18 to actuate the depressor 17 and the pointer 11 causes the engagement of contact 13and contactor 15 to energize the low temperature circuit so that the rod 25 is maintained in a position to supply heatv to the furnace. At each reciprocation of the rod 18 the contactor 61 is moved by the finger 65 into engagement with'the contact 60, thereby closing the circuit through the coil 53 and heating the arm 44 so that it moves to break the circuit closed by the'terminals 51 and 50 so that the sole- 31 is placed under control of the instrument. The periodic closing of the circuit at the contactor 61 and contact 60 causes just suflicient that is, spaced from both contacts 47 and 50. i

In case the depressor operating mechanism ceases to function and the rod 18 is held stationary with the finger 65 removed from the contactor strip 62, then the circuitof the coil 53 will be broken and the arm 44 cool, so that it returns to its normal {position with contactor 51 resting on contact 50. This closes the high temperature control circuit as follows: contact 50, arm 42. conductor 45, relay coil 46, post H, conductor 37, solenoid winding 33, conductor 36 to Service line,'ccnductor 38 to post C, conductor 52, to arm 44, and contactor 51. The closing of this circuit causes the solenoid 31 to shift the rod'25 in a direction to cutioif the supply of heat. 0

In case the depressor mechanism stops with the rod 18 in position to hold the finthe contactor 62 to ,make

under the direct control of thehigh and low heat to be maintained 1n the arm 44 to hold it in neutral position,-

contact between the contact 60 and the contactor 61, then the circuit of the coil 53 remains closed and the arm 44 is continuously heated This results in bending the arm 44 untll the contactor '48 en ages the contact 47. when the same hig temperature circuit, above described, is closed and the solenoid 31 operated to cut off the supply of heat. 1

In either of the foregoing cases the circuit closed by the thermostatic switch 40 causes the relay coil to be energized to thereby break, the circuit including the contact 68 and contactor switch 66, and as this circuit also includes contact 13 and contactor 15, thesev last two are rendered inelfective even though the pointer 11 should be bolding the contactor 15 in position to close the circuit.

It will now be apparent that a complete unitary protective means has been provided switch 40 a should be noted that the three arms 41, 42 and 44 are formed of the same gauge thermostatic metal so that the relative position of each to the other is constant regardless of variations in tempera ture of the surrounding atmosphere. The

contactor arm 44 has a double safety function in that it engages one arm to break the control circuit in case the contact mechanism stops with the contact closed, and engages the other arm to break the control circuit in case the contact mechanism stops with the contact broken.

It will be understood that the solenoid structure 31 isfonly shown by way of example and that the Wll'ldlllgS thereof may be of any st-andard;construction and not necessarily of the rever'sely wound type.

While but a single form is shown in which this invention may be embod1ed, it is to be understood that the invention is notlimited to any specific construction, but

, might be applied in various forms without departing from the spirit of the invention or-the scope of the appended claims.

Having thus described my invention, I

claim:

1. A safety system for? a control. instrument, comprising a safety circuit arranged to control a mechanism to prevent abnormal.

or danger conditions in a system cgntrolled by said instrument, a control cit-cult, means "controlled by said instrument for opening and closing said control circuit, and means actuated by said control circuit for controlling saidsafety circuit, said last means being arranged to affect said safety circuit in one manner when said control circuit is periodically closed', and to affect said safety circuit in another manner when said control circuit is continuously closed.

2. A safety system for a control instrument, comprising a safety circuit arranged to. control a mechanism to prevent abnormal or danger conditions in a system controlled by said instrument, a control circuit, means controlled by said instrument for opening and closing said control circuit, and means actuated by said control circuit for controlling said safety circuit, said last means being arranged to affect said safety circuit in one manner when said control circuit is periodically closed, and to affect said safety circuit in another manner when said .control circuit is either continuously open or continuously closed.

' 3. A safety system for a control instru- Yment, comprlsing a safety circuit arranged to control a mechanism to prevent abnormal or danger conditions in a system controlled by said instrument, a control circuit, means controlled by said instrument for opening and closing said control circuit, and means actuated by said control circuit for control lingsaid safety circuit, said last means being arranged to affect said safety circuit inone manner when said control circuit is periodically closed, and to affect said safety circuit in another manner when said control circuit is continuously open.

e 4. A safety system for a control instrument, comprising a safety circuit arranged to control a mechanism to prevent abnormal ordanger conditions in a system' controlled by said instrument, a control circuit, means controlled by said instrument for opening and closing said control circuit, and means actuated by said control circuit for controlling said safety circuit, said last means being arranged to break said safety circuit when said control circuit is periodically closed,-and to closesaid safety circuit when said control circuit is continuously closed. 5. A safety system for a control instrument, comprising a safety circuit arranged to control a mechanism to prevent abnormal or danger conditions in a system controlled by said instrument, a control circuit, means controlled by said instrument for opening and closing said control circuit, and means actuated by said control circuit for controllingsaid safety circuit, said last means being arranged to break said safety circuit when said control circuit is riodically closed, and toclos'e said safety circuit when said control circuit is continuously open.

6. A. safety system for a control instru- Ill closed, and to close &

ment, comprising a safety circuit-arranged to control a mechanism to prevent abnormal ordanger conditions in a system controlled by said instrument, a control circuit, means a ed to break said safety circuit when w sai control circuit is periodically said safety circuit when said control circuit is either continuously openor continuously closed.

A safety system for a control instru: ment, comprising a safety circuit arranged to control a mechanism-toprevent abnormal -or danger conditions ina system controlled and closing including a by. sa1d instrument, a control circuit, means controlled by said instrument. for opening said control circuit, and means temperature responsive device and a heating coil actuated by said control circuit for safety circuitin one manner when said control circuit is periodically closed, and to affect said safety circuit in another manner when said contro circuit .is continuously closed.

8. A safety system fora control instrument, comprising a safety-circuit arranged to control a mechanism to prevent abnormal or danger by 'said instrument, a control circuit, means controlled by said instrument for opening and closing said control circuit, and means including a g and a heating coil actuated by said control circuit for controlling said safety'circuit, said last means being arranged to break saidsafety circuit 'when said control circuit is periodically closed, and to close said safety circuit when, said control circuit 'is continuously closed.

9. A safety system for a control instru- .ment,-compr1sing a safety circuit arranged to control a mechanism to preventabnormal or danger conditions in a system controlled .by said instrument, a control circuit, means and closing controlled by said instrument for opening said control circuit, and means including a and a heating coil actuated by said control circuit for controlling said safety circuit, said last means being arranged-to break said safety circuit when said control circuit is periodically circuit when ously open.

10. In combination,- an electrical instrument arranged to operate a device for controlling the supply of a given medium, an electrical operating mechanism for said instrument, and means rendered operative by closed, and to close said safety safety circuit, said last-means be-- controlling said safety circuit, I said last means being arranged to afl'ect said conditions in a.system controlled temperature responsive device temperature responsive devicesaid control circuit is continu-- of safety circuit, and means controlled byisaid nasaao'z the failure of said operating mechanism to function, forcausing said device to discontinue the supply of said medium. v

11. In combination, an electrical instrument arranged to operate a device for controlling the source of heat to a heating unit,

an electrical operating mechanism for said ment arranged to operate a device for con-,

trolling the source of heat to aheating unit,

. an electrical operating mechanism for said a tempersaid deinstrument, and means, including ature responsive switch, for causing vice to cut off the source of heat rom said heating unit, said means being rendered opoperating erative by the failure of said mechanism to function.

13.In combination, an instrument arranged to o erate a device for controlling the source 0 heat to a heating unit, an operating mechanism for said instrument, and

-means including an electrical heating coil for causing said .device to cut off the source of heat from said heating unit, said means being rendered operative by the failure of said operating mechanism to function.

14. In combination, ment arranged to operate a device for controlling the source of heat to a heating unit,

an electrical instrua mechanism including a depressor bar for periodically operating said instrument, and means controlled by said depressor bar for causing said device to cut off the source of heat from said heating unit when said operating mechanism ceases to function.

15. In combination, an instrument arranged to operate a device for controlling the source of heat to a heating unit, said instrument including a low temperature circuit for causing said device to supply the source of heat, an operating mechanism for said instrument, means for actuating said device to cutoii' said source of heat from said heating unit when said operating mechanism ceases to function, and means controlled by said actuating means for breaking said low temperature circuit.

16. In combination, an instrument .ar-

ranged to operate a device forcontrolling heating unit, an opthe source of heat to a crating mechanism for safety circuit arranged to actuate said device to said instrument, a in'closed condition cut off said source heat, a switch arranged to control said operating mechanism for maintainingsaid switch in position to break said safety circuit under normal operating conditions of said mechanism, and for maintaining said switch in position to close said safety circuit under inoperative conditions of said mechanism.

17. Incombination, an instrument arranged to operate a device for controlling the source of heat to a heating unit, an operating mechanism for said instrument, a safety circuit arranged in closed condition to actuate said device to cut ofi' said source of heat, a switch arranged to control said safety circuit, and means controlled by said operating mechanism and including a heating coil for maintaining said switch in position to break said safety circuit under normal operating conditions of said mechanism, and for maintaining said switch in position to close, said safety circuit under inoperative conditions of said mechanism.

18. In co bination, an instrument arranged to operate a device for controlling the source of heat to a heating unit, an opcontrol said safety circuit, and means controlled by said operatin mechanism and including a heating coil or maintaining said switch in position to break said safety circuit under normal 0 rating conditions of said mechanism, an for maintaining said switch in position to close said safety circuit under inoperative conditions of said mechanism.

Signedat Philadelphia, county of Philadelphia, State of Pennsylvania, this 22 day of August,-1922.

CHRISTIAN WILHJ ELM. 

